Method of changing mooring anchoring legs of two ships by lifting and pulling

Abstract

The invention relates to a method of changing mooring anchoring legs of two ships by lifting and pulling. The method comprises the following steps: adjusting heading of an FPSO; loosening the anchoring legs; connecting an auxiliary lifting and pulling ship and a mooring treatment ship to a first preset position and a second preset position on a counterweight chain separately; lifting a recycling winch belt of the auxiliary lifting and pulling ship to an designated depth, and synchronously moving the ship in the reverse direction of the FPSO; adopting the mooring treatment ship to recycle the counterweight chain and a used buried cable until all the damaged section of the used buried cable is recycled on a deck, and adopting the auxiliary lifting and pulling ship to cooperate to move the ship; cutting and recycling the damaged section of the used buried cable; manufacturing a new upper cable joint of the rest section of the used buried cable, connecting the new upper cable joint with the lower cable joint of a new buried cable, and putting the connected joints in water; cooperating the mooring treatment ship and the mooring treatment ship to move the ship and lay along the originaldesign route; and tensioning the anchoring legs. With adoption of the method, the buried cable can be changed on the condition that the FPSO is in place and halt production of the FPSO is avoided, part of buried cable and the counterweight chain need to be recycled and laid only, the workload is greatly reduced, construction operation risk and operation time are reduced, and the yield loss of an oilfield is reduced.

Description

technical field [0001] The invention relates to a mooring system, and more specifically, relates to a method for replacing mooring anchor legs by pulling two ships. Background technique [0002] The internal turret single point mooring system (STP, Submerged Turret Production) is a single point mooring system widely used in floating production storage and offloading tankers (FPSO, Floating Production Storage and Offloading). The FPSO single point mooring system will have great differences in the structure and installation method of the entire mooring system according to the difference in water depth, design manufacturer and whether it can be released. The single point mooring system usually includes 6-12 anchor legs with the same structure, each anchor leg is composed of ACT chain (adjustment chain), upper anchor cable, mid-water buoy, connecting plate (triangular plate or quadrangular plate, etc.), It is composed of lower anchor cable, counterweight chain, ground cable, an...

AI Technical Summary

Problems solved by technology

[0006] Second, the construction time increases

In order to repair the ground cable, the entire anchor leg needs to be recovered and re-laid, which requires more offshore operation time

[0007] Third, the construction cost increases

When replacing mooring anchor legs in shallow water, it is necessary to use saturated divers for auxiliary operations, which increases the construction cost

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